To rationally design the best bifunctional water decomposition electrocatalyst with low cost and high activity is significant for achieving efficient conversion and storage of sustainable energy. An improved self-supporting stainless steel mesh electrocatalyst is obtained by the steps of corrosion, immersion and phosphating. The electrochemically modified stainless steel electrocatalyst exhibited excellent electrocatalytic performance for both hydrogen evolution reaction（HER） and oxygen evolution reaction（OER） in alkaline medium，displaying Tafel slope of 87.41 mV·dec-1 and 90.1 mV·dec-1，respectively. At current density of 10 mA·cm-2，the electrochemically modified stainless steel mesh electrocatalyst exhibited low overpotential of 164 mV and 240 mV，allowing it to be used as bifunctional electrocatalyst for overall water splitting with enhanced overall voltage of 1.66 V at10 mA·cm-2.